Crystal structure of akuammicine, an indole alkaloid from Catharanthus roseus.

The title compound, C20H22N2O2, an alkaloid isolated from the Madagascar periwinkle, crystallizes in P1 with two independent but closely similar mol-ecules in the unit cell. The mol-ecules are linked into pairs by two N-H⋯O=C hydrogen bonds. The absolute configuration was confirmed by anomalous dispersion effects as S at the 3 and 15 positions, and R at the 7 position.